1. Field of the Invention
The invention relates generally to an apparatus for generating an audible signal and more particularly, relates to an apparatus for generating an audible signal under water for communication between divers.
2. General Background
In the area of sport and commercial diving a variety of situations exist which require that divers have some form of communication with each other. A number of dangerous situations may arise whether diving in shallow or deep waters which may necessitate the need for signalling other divers to either warn of impending danger or signal that a diver is in need of help. This need for communication between divers also exists in non-emergency situation. Often times when diving, divers may be separated by a relatively short distance, but such distance is sufficient that hand signals may be insufficient to capture the attention of a fellow diver. In these situations, a diver may not always have tools or implements for making sufficient noise under water which will attract the attention of his fellow divers. It can be seen that a need exists for a relatively inexpensive device which would be available to all divers, which is water resistant, produces a sound to allow communication between divers and is sized small enough so that it is easily carried by a diver. Patents of which applicant is aware include the following.
U.S. Pat. No. 4,095,667 discloses a portable underwater signalling transducer for use by divers having self-contained underwater breathing apparatus (scuba) to signal to other divers as well as surface and underwater vessels. The device uses high pressure compressed air from the diver's tank to drive a hammer against a diaphragm to cause sound waves to be transmitted through the water. The device is mechanical whereas the present invention is electrical. Also, the device uses complex valving and would be prone to corrosion due to metallic construction, thus resulting in higher costs.
U.S. Pat. No. 4,312,054 discloses a device which provides a housing having a battery therein with one terminal which forms an abutment against a contact screw fixed in the housing. The second battery terminal abuts against a compression spring which holds the battery in place and provides contact with an end plug, which is removable and forms a seal against the internal walls of the housing by means of a gasket to prevent the entry of water into the housing. The opposite end of the housing is provided with a similar plug sealed by a gasket. The second plug is provided with a membrane and pressure switch. The pressure switch is activated by the membrane in response to water pressure to provide power through printed circuits provided in the housing to a transmitter which is mounted on the exterior surface of the housing. The transmitter is in communication with the printed circuits by a lead which is fed through the external wall of the housing. The device is attached to the hull of a ship and may be used to aid in locating the ship if it should sink.
U.S. Pat. No. 4,281,404 discloses a depth finding apparatus which comprises a hand held self-contained housing having a water immersible nose which carries a transducer adapted to transmit and receive sonic pulses. The housing includes transmitting and receiving circuitry having electrical connections with the transducer and located in a water tight interior. A switch is provided to operate a self-contained source of power for energizing the transmitting and receiving circuitry. The apparatus is not used for communication, but is used for determining water depth.
U.S. Pat. No. 3,469,231 discloses a device for underwater communication and location. A housing has contained therein a modulated ultrasonic frequency wave transmitter and receiver with several sonic frequency transducers. The transducers have spherical shape characteristics, but are provided with a point for locating a device. The device is also provided with a switch in the housing for alternate sending and receiving and for acoustic or optical indicating elements for receiving signals and for locating another of the same device. The device utilizes ultrasonic frequencies rather than acoustic sounding means as does the present invention and thus requires more complex electronics. This taken in combination with the fact that two of the devices are needed for them to work makes the device cost prohibitive to sport divers.
U.S. Pat. Nos. 4,297,677; 3,248,723; 3,558,822 and 3,728,670 all disclose battery powered noise generators which are portable, but do not discuss their adaptation for underwater use.
Unpatented devices of which applicant is aware include the "Sport-Phone Diver C.B." and "Wet-Beacon/Wet-Finder Electronic Navigation System." The "Sport-Phone" is a waterproof C.B. radio which may be used underwater and consists of a transceiver having the microphone attached to a regulator and a bone conduction earphone. The "Navigation System" sends out ultrasonic pulses to aid a diver in marking and relocating a specific location.